The present invention relates to methods and compositions for treating kidney disease, in particular polycystic kidney disease.
Autosomal Polycystic Kidney Disease (ADPKD) is the most prevalent, potentially fatal, inherited disease affecting the human kidney with a reported incidence of 1 out of every 500 births. It has been estimated that 500,000 persons in North America suffer from this disease of which 30,000-75,000 are Canadians. Worldwide, almost 5 million persons suffer from this debilitating disease. Polycystic kidney disease results in enlarged, cyst-filled kidneys in the abdomen producing severe, unremitting back pain, early and progressive hypertension, frequent urinary tract infections and blood in the urine. PKD also has inflammatory and other clinical components. Approximately 45% of cases can be expected to progress to end-stage renal disease (fatal) before the age of 60, adding to health care costs for dialysis treatment, hospitalization, premature morbidity due to cardiovascular and other disorders, surgeries, etc.
At present, there are no known treatments of PKD other than renal ablation, organ transplantation and cyst decompression, all costly, and sometimes life threatening. There is some evidence that, in adult humans, a slower rate of kidney deterioration is associated with a moderate protein restriction (Oldrizzi, L., et al., 1983., Kidney Int., 271:553). This therapy however, is of limited use in the growing child with PKD.
Previous studies of the inventors have shown that feeding a soy protein isolate (SPI;Supro 675 Plus HG(copyright), Protein Technologies, International, St Louis, Mo.) markedly slowed disease progression in the DBA/2FG-pcy(pcy) mouse model of ADPKD (Tomobe K et al, 1998. Am. J. Kidney Diseases. 31:55-61). However, at that time the identity of the active component of the soy protein isolate was not determined.
In view of the foregoing, there is a need in the art to develop a treatment for polycystic kidney disease.
The present inventors have determined that soyasaponin Bb is useful in treating polycystic kidney disease.
Accordingly, the present invention provides a method of treating a kidney disease comprising administering an effective amount of soyasaponin Bb or an analog thereof to an animal in need thereof.
The present invention also includes pharmaceutical and nutraceutical compositions comprising an effective amount of soyasaponin Bb or an analog thereof in admixture with suitable diluents or carriers.
The present invention further includes a novel method for the isolation of soyasaponin Bb.